linux-kernel - Re: [linus:master] [mm] c0bff412e6: stress-ng.clone.ops_per

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Message-ID: <CAGudoHGzNu4MUDyd1OeP+R=TdOzO6Nidk26_hrinBncz6FpGvw@mail.gmail.com>
Date: Wed, 14 Aug 2024 13:06:16 +0200
From: Mateusz Guzik <mjguzik@...il.com>
To: David Hildenbrand <david@...hat.com>
Cc: Yin Fengwei <fengwei.yin@...el.com>, kernel test robot <oliver.sang@...el.com>, 
	Peter Xu <peterx@...hat.com>, oe-lkp@...ts.linux.dev, lkp@...el.com, 
	linux-kernel@...r.kernel.org, Andrew Morton <akpm@...ux-foundation.org>, 
	Huacai Chen <chenhuacai@...nel.org>, Jason Gunthorpe <jgg@...dia.com>, 
	Matthew Wilcox <willy@...radead.org>, Nathan Chancellor <nathan@...nel.org>, 
	Ryan Roberts <ryan.roberts@....com>, WANG Xuerui <kernel@...0n.name>, linux-mm@...ck.org, 
	ying.huang@...el.com, feng.tang@...el.com
Subject: Re: [linus:master] [mm] c0bff412e6: stress-ng.clone.ops_per_sec -2.9% regression

On Wed, Aug 14, 2024 at 11:45 AM David Hildenbrand <david@...hat.com> wrote:
>
> On 14.08.24 06:10, Mateusz Guzik wrote:
> > On Wed, Aug 14, 2024 at 5:02 AM Yin Fengwei <fengwei.yin@...el.com> wrote:
> >>
> >> On 8/13/24 03:14, Mateusz Guzik wrote:
> >>> would you mind benchmarking the change which merely force-inlines _compund_page?
> >>>
> >>> https://lore.kernel.org/linux-mm/66c4fcc5-47f6-438c-a73a-3af6e19c3200@redhat.com/
> >> This change can resolve the regression also:
> >
> > Great, thanks.
> >
> > David, I guess this means it would be fine to inline the entire thing
> > at least from this bench standpoint. Given that this is your idea I
> > guess you should do the needful(tm)? :)
>
> Testing
>
> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
> index 5769fe6e4950..25e25b34f4a0 100644
> --- a/include/linux/page-flags.h
> +++ b/include/linux/page-flags.h
> @@ -235,7 +235,7 @@ static __always_inline int page_is_fake_head(const struct page *page)
>          return page_fixed_fake_head(page) != page;
>   }
>
> -static inline unsigned long _compound_head(const struct page *page)
> +static __always_inline unsigned long _compound_head(const struct page *page)
>   {
>          unsigned long head = READ_ONCE(page->compound_head);
>
>
> With a kernel-config based on something derived from Fedora
> config-6.8.9-100.fc38.x86_64 for convenience with
>
> CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP=y
>
> add/remove: 15/14 grow/shrink: 79/87 up/down: 12836/-13917 (-1081)
[snip]
> Total: Before=32786363, After=32785282, chg -0.00%

I guess there should be no opposition then?

Given that this is your patch I presume you are going to see this through.

I don't want any mention or cc on the patch, thanks for understanding :)

-- 
Mateusz Guzik <mjguzik gmail.com>